| 摘要 |
PURPOSE:To enable a proper pre-load value to be given by providing a pre-load detecting device detecting a pre-load value and also a decision means comparing the pre-load value with the upper limit value and lower limit value of a standard. CONSTITUTION:DC motors 1-5 are started when a signal indicating that torque transducers 1-2 for micro-torque and a stopper 2 for protection are 'ON' enters a logic circuit 36. When the outputs of a torque T1 setting device 4 and fastening torque transducers 1-3 are in agreement with one another, a comparator 6 is operated and motors 1-5 are stopped. Also, a pre-load value detected and the upper limit value and lower limit value of a pre-load torque setting device 35 are compared at a comparator 34. If the pre-load value detected is found below the lower limit value, the re-fastening of a nut is conducted, and if found above the upper limit value, the nut is loosened and a re-fastening is conducted at beneath a loosening angle as well.
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